Tractors and other work vehicles typically operate in a forward-facing mode, with one steering wheel located immediately in front of the operator. The steering wheel is used in conjunction with accelerator pedal, brake pedal and other transmission controls to drive the vehicle over the work terrain. Occasionally, it is necessary to drive the vehicle in a reverse direction, and the vehicle operator will turn his head and look behind to do this.
For some tasks, it is necessary to operate the vehicle in a reverse direction for prolonged periods of time. It has been common practice to have a second steering location for this purpose, whereby the operator moves to the second (rear-facing) steering location to operate the vehicle in reverse. Having multiple operating stations or steering wheels on a vehicle to allow prolonged reverse operation is not uncommon.
One problem in designing tractors with multiple workstations is determining how to move the seat to alternately face forward and backward.
The simplest arrangement would be to mount the seat on a single center pivot that will permit the entire seat to rotate about fixed point from a forward-facing position to a rear-facing position. In this arrangement, the seat has a pivot point located as closely as possible to the fore and aft center of the seat. The operator can release the seat and rotate it about this center pivot point.
Since the space in the cab of an agricultural tractor is limited, a simple single pivot arrangement does not provide the operator's legs with sufficient room. When the operator rotates such a seat, the operator's knees bang up against the side of the operator compartment.
Furthermore, the operating stations may be spaced so closely together that the seat must not only rotate but must also slide backward or forwards to position the operator in substantially the same position with respect to the controls of the second operating station as the operator was to the first operating station. Mere rotation of the seat around its center point may not position the operator in the proper front-to-rear position within the cab necessary to allow easy operation of controls at both workstations.
For this reason, a more complex movement of the operator seat is required. The seat should simultaneously rotate and translate with respect to the operator compartment. The prior art teaches a variety of seat arrangements that permit simultaneous seat translation and rotation.
U.S. Pat. No. 6,513,872, for example, shows a piece of furniture with a seat portion that can be pivoted with respect to an adjacent seat portion and to fixed back arrests to convert from a chaise lounge (plus adjacent chair) to a sofa by pivoting 90°. The back portions are fixed, and the pivoting seat portion is supported on two parallel plates that translate and rotate with respect to each other. The plates are coupled together using a cam slot that defines a linear path of translation for the center of the seat and a control link that controls the angle of rotation of the seat. Only one seat portion is moved. The other seat portion stays stationary.
U.S. Pat. No. 1,916,800 shows a seat support for simultaneously reversing two seats for seating two people side-by-side while laterally shifting the seat. The seat support is coupled directly to a pitch seat and has two cam slots, each with a follower. One slot is a straight line and the other is a large radius curve. Both of the two seats can be simultaneously rotated 180°.
U.S. Pat. No. 2,200,904 shows a pair of seats for seating to people side-by-side in a bus or train, both of which are supported on a common seat support having two parallel plates, one having a U-shaped cam slot that engages a pin in the other plate and a control link pivotally coupled to both plates. Both seats can be simultaneously rotated 180°.
U.S. Pat. No. 1,803,063 similarly shows a pair of seats adjacent one another for a railroad coach, both of which are fixed to a common central seat support, the seat support that has two cam slots, one straight, and one curved, each cam slot having a corresponding follower. Both seats can be simultaneously rotated 180°.
U.S. Pat. No. 2,146,187 shows two seats adjacent to one another for a railway coach or bus. The seats are fixed to a common support, which is in turn pivotally coupled to the vehicle by two pivoting mechanical links with cam followers at the end that are guided through a “Y”-shaped slot.
U.S. Pat. No. 4,417,715 shows two seats adjacent to one another and facing the same direction that are coupled to a common base for use in intercity buses. Both seats are coupled to a common seat support that includes a “Y”-shaped cam slot in which move two cam followers fixed with respect to both seats. To insure the cam followers never both go into the same branch of the “Y”, a spring loaded switch lever is provided that in blocks one cam follower.
All of the seating systems illustrated in the foregoing patents are configured to rotate two seats 180°, while at the same time causing each of the two seats to exchange places with the other of the two seats. Thus, each seat of the two seats in each pair of seats both (1) rotates 180° and (2) translates sideways one complete seat width.
There is not enough space in a tractor cab to have two seats side-by-side. Furthermore, even if one of the two seats in the prior art references was removed, the remaining seat would still be translated sideways one entire seat width. The amount of room required to rotate the seats is greater than the amount provided in the cab of an agricultural tractor.
Another drawback to these prior art mechanisms as their inability to rotate the seat 180° while keeping the seat oriented on the same longitudinal axis. When a seat in an agricultural tractor is rotated it must stay long the same central longitudinal centerline. It must rotate, generally, about a point right underneath the operator's posterior. Only in this manner can the operator the located along the centerline of the vehicle in both the front-facing and a rear-facing direction. The prior art embodiments not only rotate two seats 180°, they also move the seats sideways by one seat width.
What is needed, therefore is an operator seat for a work vehicle that rotates 180° to face forward and backwards.
What is also needed is a seat that is centered on the longitudinal axis of the vehicle in both of its 180° opposed positions.
What is also needed is a single width operator seat for work vehicle that fits into the narrow confines an agricultural tractor compartment.
What is also needed is a seat that can be rotated in a confined space without the operator having to rise from his seated position.
What is also needed is a seat that rotates in place between two opposed vehicle operating stations and requiring minimal adjustment and room to be located in proper position next to the operator controls.
These and other objects of the invention are provided by the pivoting operator seat described below.